Unit 7 Regulation and Body Systems
Chapters 39,40,41,42,43,44,48,49
AP Biology 2012-13
Enduring understanding 2.A: Growth, reproduction and maintenance of the organization of living
systems require free energy and matter.
Living systems require energy to maintain order, grow and reproduce. In accordance with the
laws of thermodynamics, to offset entropy, energy input must exceed energy lost from and used by an
organism to maintain order. Organisms use various energy-related strategies to survive; strategies
include different metabolic rates, physiological changes, and variations in reproductive and offspringraising strategies. Not only can energy deficiencies be detrimental to individual organisms, but changes
in free energy availability also can affect population size and cause disruptions at the ecosystem level
Essential knowledge 2.A.1: All living systems require constant input of free energy.
Evidence of student learning is a demonstrated understanding of each of the following:
1. Organisms use various strategies to regulate body temperature and metabolism.
To foster student understanding of this concept, instructors can choose an illustrative example such as:
• Endothermy (the use of thermal energy generated by metabolism to maintain homeostatic body
temperatures)
• Ectothermy (the use of external thermal energy to help regulate and maintain body temperature)
• Elevated floral temperatures in some plant species
2. Reproduction and rearing of offspring require free energy beyond that used for maintenance and
growth. Different organisms use various reproductive strategies in response to energy availability.
To foster student understanding of this concept, instructors can choose an illustrative example such as:
• Seasonal reproduction in animals and plants
• Life-history strategy (biennial plants, reproductive diapause)
3. There is a relationship between metabolic rate per unit body mass and the size of multicellular
organisms — generally, the smaller the organism, the higher the metabolic rate.
Enduring understanding 2.C: Organisms use feedback mechanisms to regulate growth and
reproduction, and to maintain dynamic homeostasis.
Organisms respond to changes in their internal and external environments through behavioral
and physiological mechanisms, such as photoperiodism in plants, hibernation and migration in animals,
and shivering and sweating in humans. Organisms use negative feedback mechanisms to maintain their
internal environments by returning the changing condition back to its target set point, while positive
feedback mechanisms amplify responses. Examples of negative feedback responses include temperature
regulation in animals and plant responses to drought; examples of positive feedback mechanisms are
the onset of labor in childbirth and ripening of fruit. Alterations in feedback mechanisms can have
deleterious effects, including diabetes and Graves’ disease in humans and the inability of plants to
tolerate water stress during drought.
Essential knowledge 2.C.1: Organisms use feedback mechanisms to maintain their internal
environments and respond to external environmental changes.
a. Negative feedback mechanisms maintain dynamic homeostasis for a particular condition (variable) by
regulating physiological processes, returning the changing condition back to its target set point.
To foster student understanding of this concept, instructors can choose an illustrative example such as:
• Operons in gene regulation
• Temperature regulation in animals
• Plant responses to water limitations
b. Positive feedback mechanisms amplify responses and processes in biological organisms. The variable
initiating the response is moved farther away from the initial set-point. Amplification occurs when the
stimulus is further activated which, in turn, initiates anadditional response that produces system
change.
Students should be able to demonstrate understanding of the above concept by using an illustrative
example such as:
• Lactation in mammals
• Onset of labor in childbirth
• Ripening of fruit
c. Alteration in the mechanisms of feedback often results in deleterious consequences.
To foster student understanding of this concept, instructors can choose an illustrative example such as:
• Diabetes mellitus in response to decreased insulin
• Dehydration in response to decreased antidiuretic hormone (ADH)
• Graves’ disease (hyperthyroidism)
• Blood clotting
LO 2.15 The student can justify a claim made about the effect(s) on a biological system at the molecular,
physiological or organismal level when given a scenario in which one or more components within a
negative regulatory system is altered. [See SP 6.1]
LO 2.16 The student is able to connect how organisms use negative feedback to maintain their internal
environments. [See SP 7.2]
LO 2.17 The student is able to evaluate data that show the effect(s) of changes in concentrations of key
molecules on negative feedback mechanisms. [See SP 5.3]
LO 2.18 The student can make predictions about how organisms use negative feedback mechanisms to
maintain their internal environments. [See SP 6.4]
LO 2.19 The student is able to make predictions about how positive feedback mechanisms amplify
activities and processes in organisms based on scientific theories and models. [See SP 6.4]
LO 2.20 The student is able to justify that positive feedback mechanisms amplify responses in organisms.
[See SP 6.1]
Essential knowledge 2.C.2: Organisms respond to changes in their external environments.
a. Organisms respond to changes in their environment through behavioral and physiological
mechanisms.
To foster student understanding of this concept, instructors can choose an illustrative example such as:
• Photoperiodism and phototropism in plants
• Hibernation and migration in animals
• Taxis and kinesis in animals
• Chemotaxis in bacteria, sexual reproduction in fungi
• Nocturnal and diurnal activity: circadian rhythms
• Shivering and sweating in humans
LO 2.21 The student is able to justify the selection of the kind of data needed to answer scientific
questions about the relevant mechanism that organisms use to respond to changes in their external
environment. [See SP 4.1]
Enduring understanding 2.D: Growth and dynamic homeostasis of a biological system are influenced
by changes in the system’s environment.
All biological systems, from cells to ecosystems, are influenced by complex biotic and abiotic
interactions. The availability of resources influences activities in cells and organisms; examples include
responses to cell density, biofilm(s) formation, temperature responses, and responses to nutrient and
water availability. The availability of resources affects a population’s stability in size and its genetic
composition; examples include birth rates versus death rates from bacteria to mammals and global
distribution of food for humans.
Homeostatic mechanisms reflect both continuity due to common ancestry and change due to
evolution in different environments. Supporting evidence includes a sampling of homeostatic control
systems that are conserved across biological domains. Organisms have evolved various mechanisms for
obtaining nutrients and getting rid of wastes, including gas exchange, osmoregulation and nitrogenous
waste production. Disturbances to dynamic homeostasis effect biological processes, and plants and
animals have evolved a variety of defenses against infections and other disruptions to homeostasis
including immune responses. At the ecosystem level, disruptions impact the balance of the ecosystem
and the interactions between specific organisms therein
Essential knowledge 2.D.2: Homeostatic mechanisms reflect both common ancestry and divergence
due to adaptation in different environments.
a. Continuity of homeostatic mechanisms reflects common ancestry, while changes may occur in
response to different environmental conditions. [See also 1.B.1]
b. Organisms have various mechanisms for obtaining nutrients and eliminating wastes.
To foster student understanding of this concept, instructors can choose an illustrative example such as:
• Gas exchange in aquatic and terrestrial plants
• Digestive mechanisms in animals such as food vacuoles, gastrovascular cavities, one-way digestive
systems
• Respiratory systems of aquatic and terrestrial animals
• Nitrogenous waste production and elimination in aquatic and terrestrial animals
c. Homeostatic control systems in species of microbes, plants and animals support common ancestry.
[See also 1.B.1]
To foster student understanding of this concept, instructors can choose an illustrative example such as
the comparison of:
• Excretory systems in flatworms, earthworms and vertebrates]
• Osmoregulation in bacteria, fish and protists
• Osmoregulation in aquatic and terrestrial plants
• Circulatory systems in fish, amphibians and mammals
• Thermoregulation in aquatic and terrestrial animals (countercurrent exchange mechanisms)
LO 2.25 The student can construct explanations based on scientific evidence that homeostatic
mechanisms reflect continuity due to common ancestry and/or divergence due to adaptation in
different environments. [See SP 6.2]
LO 2.26 The student is able to analyze data to identify phylogenetic patterns or relationships, showing
that homeostatic mechanisms reflect both continuity due to common ancestry and change due to
evolution in different environments. [See SP 5.1]
LO 2.27 The student is able to connect differences in the environment with the evolution of homeostatic
mechanisms.
Essential knowledge 2.D.3: Biological systems are affected by disruptions to their dynamic
homeostasis.
a. Disruptions at the molecular and cellular levels affect the health of the organism.
To foster student understanding of this concept, instructors can choose an illustrative example such as:
• Physiological responses to toxic substances
• Dehydration
• Immunological responses to pathogens, toxins and allergens
LO 2.28 The student is able to use representations or models to
analyze quantitatively and qualitatively the effects of disruptions to dynamic homeostasis in biological
systems. [See SP 1.4]
Essential knowledge 2.D.4: Plants and animals have a variety of chemical defenses against infections
that affect dynamic homeostasis.
a. Plants, invertebrates and vertebrates have multiple, nonspecific immune responses.
Students should be able to demonstrate understanding of the above concept by using an illustrative
example such as:
• Invertebrate immune systems have nonspecific response mechanisms, but they lack pathogen-specific
defense responses.
• Plant defenses against pathogens include molecular recognition systems with systemic responses;
infection triggers chemical responses that destroy infected and adjacent cells, thus localizing the effects.
• Vertebrate immune systems have nonspecific and nonheritable defense mechanisms against
pathogens.
b. Mammals use specific immune responses triggered by natural or artificial agents that disrupt dynamic
homeostasis.
Evidence of student learning is a demonstrated understanding of each of the following:
1. The mammalian immune system includes two types of specific responses: cell mediated and humoral.
2. In the cell-mediated response, cytotoxic T cells, a type of lymphocytic white blood cell, “target”
intracellular pathogens when antigens are displayed on the outside of the cells.
3. In the humoral response, B cells, a type of lymphocytic white blood cell, produce antibodies against
specific antigens.
4. Antigens are recognized by antibodies to the antigen.
5. Antibodies are proteins produced by B cells, and each antibody is specific to a particular antigen.
6. A second exposure to an antigen results in a more rapid and enhanced immune response.
✘✘Memorization of the structures of specific antibodies is beyond the scope of the course and the AP
Exam
LO 2.29 The student can create representations and models to describe immune responses. [See SP 1.1,
1.2]
LO 2.30 The student can create representations or models to describe nonspecific immune defenses in
plants and animals. [See SP 1.1, 1.2]
Enduring understanding 3.E: Transmission of information results in changes within and between
biological systems.
Evolution operates on genetic information that is passed to subsequent generations. However,
transmission of nonheritable information also determines critical roles that influence behavior within
and between cells, organisms and populations. These responses are dependent upon or influenced by
underlying genetic information, and decoding in many cases is complex and affected by external
conditions. For example, biological rhythms, mating behaviors, flowering, animal communications and
social structures are dependent on and elicited by external signals and may encompass a range of
responses and behaviors.
Organ systems have evolved that sense and process external information to facilitate and
enhance survival, growth and reproduction in multicellular organisms. These include sensory systems
that monitor and detect physical and chemical signals from the environment and other individuals in the
population and that influence an animal’s well-being. The nervous system interacts with sensory and
internal body systems to coordinate responses and behaviors, ranging from movement to metabolism to
respiration. Loss of function and coordination within the nervous system often results in severe
consequences, including changes in behavior, loss of body functions and even death.
Knowledge and understanding of the structures and functions of the nervous system are needed
to understand this coordination. The features of an animal’s nervous system are evolutionarily
conserved, with the basic cellular structure of neurons the same across species. The physiological and
cellular processes for signal formation and propagation involve specialized membrane proteins, signaling
molecules and ATP.
Neurological signals can operate and coordinate responses across significant distances within an
organism. The brain serves as a master neurological center for processing information and directing
responses, and different regions of the brain serve different functions. Structures and associated
functions for animal brains are products of evolution, and increasing complexity follows evolutionary
lines.
Essential knowledge 3.E.2: Animals have nervous systems that detect external and internal signals,
transmit and integrate information, and produce responses.
a. The neuron is the basic structure of the nervous system that reflects function.
Evidence of student learning is a demonstrated understanding of each of the following:
1. A typical neuron has a cell body, axon and dendrites. Many axons have a myelin sheath that acts as an
electrical insulator.
2. The structure of the neuron allows for the detection, generation, transmission and integration of
signal information.
3. Schwann cells, which form the myelin sheath, are separated by gaps of unsheathed axon over which
the impulse travels as the signal propagates along the neuron.
b. Action potentials propagate impulses along neurons.
Evidence of student learning is a demonstrated understanding of each of the following:
1. Membranes of neurons are polarized by the establishment of electrical potentials across the
membranes.
2. In response to a stimulus, Na+ and K+ gated channels sequentially open and cause the membrane to
become locally depolarized.
3. Na+/K+ pumps, powered by ATP, work to maintain membrane potential.
c. Transmission of information between neurons occurs across synapses.
Evidence of student learning is a demonstrated understanding of each of the following:
1. In most animals, transmission across synapses involves chemical messengers called
neurotransmitters.
To foster student understanding of this concept, instructors can choose an illustrative example such as:
• Acetylcholine
• Epinephrine
• Norepinephrine
• Dopamine
• Serotonin
• GABA
2. Transmission of information along neurons and synapses results in a response.
3. The response can be stimulatory or inhibitory.
d. Different regions of the vertebrate brain have different functions
To foster student understanding of this concept, instructors can choose an illustrative example such as:
• Vision
• Hearing
• Muscle movement
• Abstract thought and emotions
• Neuro-hormone production
• Forebrain (cerebrum), midbrain (brainstem) and hindbrain (cerebellum)
• Right and left cerebral hemispheres in humans
✘✘ The types of nervous systems, development of the human nervous system, details of the various
structures and features of the brain parts, and details of specific neurologic processes are beyond the
scope of the course and the AP Exam.
LO 3.43 The student is able to construct an explanation, based on scientific theories and models, about
how nervous systems detect external and internal signals, transmit and integrate information, and
produce responses. [See SP 6.2, 7.1]
LO 3.44 The student is able to describe how nervous systems detect external and internal signals. [See
SP 1.2]
LO 3.45 The student is able to describe how nervous systems transmit information. [See SP 1.2]
LO 3.46 The student is able to describe how the vertebrate brain integrates information to produce a
response. [See SP 1.2]
LO 3.47 The student is able to create a visual representation of complex nervous systems to
describe/explain how these systems detect external and internal signals, transmit and integrate
information, and produce responses. [See SP 1.1]
LO 3.48 The student is able to create a visual representation to describe how nervous systems detect
external and internal signals. [See SP 1.1]
LO 3.49 The student is able to create a visual representation to describe how nervous systems transmit
information. [See SP 1.1]
LO 3.50 The student is able to create a visual representation to describe how the vertebrate brain
integrates information to produce a response. [See SP 1.1]
Big Idea 4: Biological systems interact, and these systems and their interactions possess complex
properties.
All biological systems are composed of parts that interact with each other.
These interactions result in characteristics not found in the individual parts alone. In other words, “the
whole is greater than the sum of its parts.” All biological systems from the molecular level to the
ecosystem level exhibit properties of biocomplexity and diversity. Together, these two properties
provide robustness to biological systems, enabling greater resiliency and flexibility to tolerate and
respond to changes in the environment. Biological systems with greater complexity and diversity often
exhibit an increased capacity to respond to changes in the environment.
At the molecular level, the subcomponents of a biological polymer determine the properties of
that polymer. At the cellular level, organelles interact with each other as part of a coordinated system
that keeps the cell alive, growing and reproducing. The repertory of subcellular organelles and
biochemical pathways reflects cell structure and differentiation. Additionally, interactions between
external stimuli and gene expression result in specialization and divergence of cells, organs and tissues.
Interactions and coordination between organs and organ systems determine essential biological
activities for the organism as a whole. External and internal environmental factors can trigger responses
in individual organs that, in turn, affect the entire organism.
Enduring understanding 4.A: Interactions within biological systems lead to complex properties.
All biological systems, from cells to ecosystems, are composed of parts that interact with each
other. When this happens, the resulting interactions enable characteristics not found in the individual
parts alone. In other words, “the whole is greater than the sum of its parts,” a phenomenon sometimes
referred to as “emergent properties.”
Organisms exhibit complex properties due to interactions of their constituent parts, and
interactions and coordination between organs and organ systems provide essential biological activities
for the organism as a whole. Examples include the vessels and hearts of animals and the roots and
shoots of plants. Environmental factors such as temperature can trigger responses in individual organs
that, in turn, affect the entire organism.
.
Essential knowledge 4.A.4: Organisms exhibit complex properties due to interactions between their
constituent parts.
a. Interactions and coordination between organs provide essential biological activities.
To foster student understanding of this concept, instructors can choose an illustrative example such as:
• Stomach and small intestines
• Kidney and bladder
• Root, stem and leaf
b. Interactions and coordination between systems provide essential biological activities.
To foster student understanding of this concept, instructors can choose an illustrative example such as:
• Respiratory and circulatory
• Nervous and muscular
• Plant vascular and leaf
LO 4.8 The student is able to evaluate scientific questions concerning organisms that exhibit complex
properties due to the interaction of their constituent parts. [See SP 3.3]
LO 4.9 The student is able to predict the effects of a change in a component(s) of a biological system on
the functionality of an organism(s). [See SP 6.4]
LO 4.10 The student is able to refine representations and models to illustrate biocomplexity due to
interactions of the constituent parts. [See SP 1.3]
Enduring understanding 4.C: Naturally occurring diversity among and between components within
biological systems affects interactions with the environment.
A biological system that possesses many different components often has greater flexibility to
respond to changes in its environment. This phenomenon is sometimes referred to as “robustness.”
Variation in molecular units provides cells with a wider range of functions; cells with multiple copies of
genes or heterozygous genes possess a wider range of functions compared to cells with less genetic
diversity, while cells with myriad enzymes can catalyze myriad chemical reactions
Essential knowledge 4.C.1: Variation in molecular units provides cells with a wider range of functions.
a. Variations within molecular classes provide cells and organisms with a wider range of functions. [See
also 2.B.1, 3.A.1, 4.A.1, 4.A.2]
To foster student understanding of this concept, instructors can choose an illustrative example such as:
• Different types of phospholipids in cell membranes
• Different types of hemoglobin
• MHC proteins
• Chlorophylls
• Molecular diversity of antibodies in response to an antigen